the half-covered lens is sort of a minor thread on the list, but I couldn't
help but comment.
Professional photographers use this technique often when photographing
They cover the top-half of the lens and photograph the happy couple
at the altar, or kneeling, or some solemn moment.
The shutter is reset without advancing the film. Depending upon the
camera, one can hold in the bottom rewind button while advancing the
film, or rewind the film one frame after the camera has set itself
for the next picture.
Then the bottom half of the lens is covered as a second picture of
the church steeple, or stained glass window, or church front, or
whatever it taken.
The net result is a superimposing of two images that is very effective and
difficult to do by other means.
This is clearly an optics effect that is more hands-on, or emperical, than